Have you ever wondered ...how your fridge cools the food
you put inside it? This is a good practical example of the gas laws in action.
Temperature, pressure and volume all have a part to play in the cooling process.

CLICK HERE to see an animated diagram of how a fridge works. (Close the new
window to return to this page).

Gas is drawn at low pressure and low
temperature through a line. The gas is compressed using electricity to a higher pressure
and its temperature rises (just like a bicycle pump which gets warmer when you are pumping
up a tyre). It is then transferred to a condenser where the heat is removed and the gas
begins to condense into a liquid. The heat is released via cooling fins on the back of the
fridge unit. The liquid then goes through an expansion device where its pressure is
suddenly lowered, it expands and some of the liquid turns very quickly into a vapour. This
change of state has a cooling effect. Now the cold vapour and liquid are able to cool the
air in the cabinet of the refrigerator through an evaporator. The liquid absorbs the
warmth from the air inside the refrigerator and turns back into a low temperature gas, at
low pressure. It now starts its journey again through the compressor.